1. Field of the Invention
The present invention relates to a method of vaporizing from container an organometallic compound which is solid at normal temperature. Specifically, the invention relates to a method of vaporizing a solid organometallic compound in a container wherein the solid organometallic compound is vaporized at a constant concentration and the remaining amount of the solid organometallic compound in the container is effectively reduced.
2. Description of the Related Art
An organometallic compound such as trimethylindium is useful, for example, as a raw material for a compound semiconductor. Generally, a container filled with an organometallic compound is disposed in a temperature-controlled bath at predetermined temperature, a carrier gas such as hydrogen is introduced into the container so as to contact with the organometallic compound in the container, and then the gas containing the organometallic compound of predetermined concentration is taken out of the container to vaporize the organometallic compound to a production apparatus for a compound semiconductor.
A cylindrical container made of stainless steel is typically used as the container, and the container having various characteristics in the structure of the bottom, an inlet tube of carrier gas, an outlet tube of the gas or the like has been known for improving thermal efficiency, controllability of concentration of an organometallic compound, usage rate of the organometallic compound in the container and the like. The larger-sized container has been used from the viewpoint of productivity improvement.
In the case where an organometallic compound is solid at normal temperature, the compound is filled into the container in the shape of small grains, or the organometallic compound supported on an inert support obtained by rotating an inert support and a molten organometallic compound is filled into the container.
In the case of being filled an organometallic compound in the shape of small grains into the container, a constant concentration of the organometallic compound in the gas to be vaporized can not be performed, because it is difficult to maintain the contact condition between a carrier gas and an organometallic compound uniform, caused by becoming a smaller grain size by vaporization or accumulating on the bottom of the container to form a flow path for passing the carrier gas.
In the case where an organometallic compound is filled into a container in the shape of being supported by the inert support, the organometallic compound is not supported uniformly and sufficiently, so that a constant concentration of the organometallic compound is not continuously vaporized to occasionally lower usage rate of the organometallic compound in the container.
A method containing a step of filling a supporting material having a porosity of 50 to 80% by volume into a container by 50 to 80% by volume with respect to the container capacity, a step of filling a granular solid material of an organometallic compound into the container, and a step of supporting in the container by melting and rotating the support material and the organometallic compound, has been known as an example of a support method (refer to JP No. 8-299778 A).
However, even this method is not necessarily sufficient, and a method of vaporizing a solid organometallic compound has been desired such that an organometallic compound which is solid at normal temperature can be vaporized at a constant concentration and the usage rate of the organometallic compound can be improved.